Rubber surface treatment and products derived therefrom

Abstract

The treatment of an uncured or partially cured rubber surface with a solvent mixture of a blend of n-heptane and iso-heptane. The treatment is to remove surface bloom and/or freshen the surface and to maintain or increase building tack. Cured adhesion can also be enhanced or maintained. An appropriate solvent mixture is provided. An article can be produced thereby as a cured assembly of rubber components. In one aspect, a purpose is to provide a suitable solvent mixture treatment of an uncured or partially cured rubber surface with a solvent mixture which has an acceptably minimal aromatic content, suitable drying time on the rubber surface and an acceptable odor in the workplace.

What is claimed is: 
     
       1. A method of treating a rubber surface which comprises treating at least one surface of an uncured or partially cured rubber article with a hydrocarbon solvent mixture and drying said treated surface wherein said solvent mixture has an aromatic hydrocarbon content, if any, of less than one (1) weight percent, including a benzene content, if any, of less than 0.01 weight percent, and is comprised of, based on 100 parts by weight, (A) about 10 to about 35 parts by weight of n-heptane, and (B) about 65 to about 85 parts by weight of iso-heptane, wherein said solvent mixture is characterized by having a KB value in a range of about 27 to about to about 31 and the solvent mixture has an initial boiling point of a minimum of at least about 85° C. and a maximum dry point of less than about 106° C. 
     
     
       2. The method of claim 1 characterized in that said hydrocarbon solvent mixture also contains up to about 18 percent by weight, based on the total solvent, of at least one additional liquid saturated alkyl branched aliphatic hydrocarbon having from 6 to 8 carbon atoms and/or liquid saturated alicyclic hydrocarbon having from 5 to 7 carbon atoms, exclusive of cyclohexane, and so long as the KB value of the overall solvent mixture is in the said range of about 27 to about to about 31 and the solvent mixture has an initial boiling point of a minimum of at least about 85° C. and a maximum dry point of less than about 106° C. 
     
     
       3. The method of claim 1 characterized in that said hydrocarbon solvent mixture is in a form of a cement composed of a mixture of said solvent and a solution and/or suspension of compounded rubber therein. 
     
     
       4. The method of claim 2 characterized in that said hydrocarbon solvent mixture is in a form of a cement composed of the said solvent and a solution and/or suspension of compounded rubber therein. 
     
     
       5. A method of adding building tack to a rubber surface characterized by treating at least one surface of an uncured or partially cured rubber article with the hydrocarbon solvent mixture according to claim 1 and drying said treated surface. 
     
     
       6. A method of adding building tack to a rubber surface characterized by treating at least one surface of an uncured or partially cured rubber article with the hydrocarbon mixture according to claim 2 and drying said treated surface. 
     
     
       7. The method of claim 6 characterized in that said uncured rubber is comprised of at least one of EPDM, butyl rubber and halobutyl rubber. 
     
     
       8. The method of claim 6 characterized in that said uncured or partially cured rubber is comprised of a high unsaturation diene derived rubber. 
     
     
       9. A method of freshening a rubber surface characterized by treating at least one surface of an uncured or partially cured rubber article with the hydrocarbon solvent mixture according to claim 1 and drying the treated surface. 
     
     
       10. A method of freshening a rubber surface characterized by treating at least one surface of an uncured or partially cured rubber article with the hydrocarbon solvent mixture according to claim 2 and drying the treated surface. 
     
     
       11. A method of producing a rubber product which comprises the steps of (A) treating a surface of a first curable rubber article with a hydrocarbon solvent to add building tack to said treated surface and remove surface bloom therefrom, (B) adhering a second rubber article, selected from curable and cured rubber articles, to the said treated surface of the first rubber article to create an assembly thereof, and (C) submitting said assembly to rubber curing conditions of elevated temperature and pressure; characterized in that said surface of said first curable rubber article is treated according to the method of claim 1. 
     
     
       12. The method of claim 11 characterized in that the said rubber article is treated by the method of claim 2. 
     
     
       13. The method of claim 11 characterized in that the said rubber article is treated by the method of claim 3. 
     
     
       14. The method of claim 11 characterized in that the said rubber article is treated by the method of claim 4.